Grinder

ABSTRACT

A grinder includes a motor, a housing that houses the motor, a spindle that projects from the housing and is driven by the motor, and thereby rotates relative to the housing, and a wheel cover that is disposed on an outer-circumference side of the spindle and is configured to cover a portion of a tool accessory attached to the spindle. The grinder also includes a holding device for holding the wheel cover on the housing such that the arrangement and position of the wheel cover around the spindle can be changed but such that the wheel cover is not readily removable from the housing.

CROSS-REFERENCE

This application claims priority to Japanese patent application serialnumber 2015-178689, filed on Sep. 10, 2015, the contents of which areincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a grinder that performs processing,such as grinding, polishing, cutting, or the like, on a workpiece.

BACKGROUND ART

A grinder comprises a spindle that is rotationally driven by a motor.The spindle protrudes from a housing, in which the motor is housed, anda discoidal (disk-shaped) tool accessory (tip tool) is attached to thetip of the spindle. As a result, the tool accessory is rotated by therotation of the spindle, and processing of the workpiece can beperformed.

A wheel cover, which covers part of the tool accessory, may be providedon an outer-circumference side of the spindle to which the toolaccessory is attached, as disclosed, e.g., in Japanese Laid-open PatentPublication numbers 2013-78823 and 2013-226617.

SUMMARY OF THE INVENTION

In prior art devices, the wheel cover is detachably mounted around aprotruding part, in which the spindle protrudes from the housing.Consequently, if the wheel cover is removed from the housing by a user,the processing work is performed on the workpiece with the entire toolaccessory (e.g., a cutting blade) is exposed.

Accordingly, it is an object of the present teachings is to disclose agrinder that prevents, or at least discourages, a user from removing thewheel cover and then using the grinder with the wheel cover removed inan unsafe manner.

A grinder according to one aspect of the present teachings comprises: amotor; a housing that houses the motor; and a spindle that projects fromthe housing and is driven by the motor, and thereby rotates inside thehousing.

In addition, a wheel cover is disposed on an outer-circumference side ofthe spindle projecting from the housing and is designed to cover aportion of a tool accessory attached to the spindle. The wheel cover isheld on the housing by one or more holding members, which is (are each)configured as a separate structure from the wheel cover, and thearrangement and position of the wheel cover around the spindle can bechanged. The one or more holding members preferably retain or hold thewheel cover on the housing in an undetachable and/or captive manner, orat least in a manner that the wheel cover is not readily or easilyremovable from the housing, as will be further explained below.

According to such a grinder, to remove the wheel cover from the grinder,it is necessary to remove the holding member(s) from the wheel cover,the housing, and the like, and that removal work is labor-intensive.Consequently, it is possible to discourage or prevent the user fromremoving the wheel cover and then using the grinder with the wheel coverremoved.

In addition, even though the wheel cover is fixed to the housing byusing the holding member(s), the arrangement of the wheel cover aroundthe spindle can be changed; consequently the position of the wheelcover, e.g., its rotational position, can be adjusted as appropriateduring usage of the grinder, thereby maintaining this ergonomic aspect(usability) of conventional grinders while making the device safer touse.

In such an embodiment, the housing includes a mounting portion, to whichthe wheel cover is attached, that has a circular-cylinder shape thatsurrounds the spindle; the wheel cover may comprise acircular-ring-shaped mounting part that is capable of being externallyfitted onto the mounting portion of the housing.

Furthermore, in such an embodiment, a slit may be provided in thecircular-ring-shaped mounting part of the wheel cover in anouter-circumferential direction of the mounting portion of the housing,and the (each) holding member may comprise a rivet or a screw that isinserted into that slit.

In such a design, the rivet or the screw is inserted into the slit, oneend of the rivet or the screw is fixed to the mounting portion of thehousing, and a head on the other-end side of the rivet or the screw ismade larger than the width of the slit, thereby making it possible tofirmly hold (retain) the wheel cover on the housing by using the holdingmember(s).

Furthermore, in such a design, if the (each) holding member comprises arivets, then, to remove the wheel cover from the housing, the head ofthe rivet must be removed using a tool, and that removal work would beextremely labor-intensive. Consequently, such a design further preventsor discourages the removal of the wheel cover.

On the other hand, if the (each) holding members comprises a screws,then the screw could be easily removed if its head has a shape (e.g., aplus (+) shape, a minus (−) shape, or the like) that corresponds to acommon tool (e.g., a flat-head screwdriver or a Phillips-headscrewdriver). Therefore, in such an embodiment, the head of the screwshould preferably be crushed or otherwise deformed, or should be madesuch that the screw cannot be turned, such as by using an adhesive orthe like.

In addition, if the head of the screw is made into a shape that can mateonly with a special tool that is not commercially available, then notonly is it possible to more effectively discourage or even prevent theremoval of the wheel cover, but it becomes possible to remove the screwonly by using a special tool. Accordingly, in such a design, thereplacement of the wheel cover can be effected by an authorized repairperson in a simple manner without damaging the grinder, peripheralmembers, and the like.

In another embodiment of the present teachings, two or more of theholding members may be distributed over and fixed at a plurality oflocations of the outer circumference of the mounting portion of thehousing. In this case, the wheel cover can be held on the housing at aplurality of locations using the holding members. Therefore, tilting ofthe center axis of the wheel cover with respect to the center axis ofthe mounting portion of the housing can be prevented. Accordingly, workefficiency is improved when the wheel cover is rotated around thespindle in order to adjust the (rotational) position of the wheel cover.

In addition, a tightening member may be provided to tighten and therebyfix the circular-ring-shaped mounting part on the outer circumference ofthe mounting portion of the housing. The tightening member may beprovided on the mounting part of the wheel cover. In such an embodiment,the wheel cover can be positioned with respect to and fixed on thehousing by the tightening member. Therefore it is possible to preventthe position of the wheel cover from shifting with respect to the toolaccessory during usage of the grinder and to prevent degradation in theusability of the grinder.

Moreover, similar to the above-described grinder, a grinder according toanother aspect of the present teachings comprises: a motor; a housingthat houses the motor; and a spindle that projects from the housing andis driven by the motor, and thereby rotates inside the housing.

In addition, a wheel cover is provided for covering a portion of a toolaccessory attached to the spindle and is disposed on anouter-circumference side of the spindle projecting from the housing. Thewheel cover is undetachably held on the housing.

Accordingly, in such a grinder, the wheel cover can no longer be removedfrom the grinder without destroying the wheel cover or portions thereof,thereby preventing or at least significantly discouraging the user fromremoving the wheel cover and then using the grinder with the wheel coverremoved.

In such an embodiment, if the housing has a mounting portion, on whichthe wheel cover is attached, that has a circular-cylinder shape thatsurrounds the spindle and if the wheel cover comprises acircular-ring-shaped mounting part capable of being externally fittedonto the mounting portion of the housing, then the grinder may comprisethe following parts.

That is, one of an outer circumference of the mounting portion of thehousing and an inner circumference of the mounting part of the wheelcover may have a groove formed along a circumferential direction, andthe other one may have a projection or a ridge, which is inserted intothe groove and is capable of sliding within the groove, formed thereon.

In this way, the mounting portion of the housing and the mounting partof the wheel cover are coupled by the groove and the projection or theridge; therefore, the wheel cover can be rotated with respect to thehousing in the circumferential direction and cannot move in thecenter-axis direction.

Consequently, it is possible to adjust the arrangement and position(e.g., rotational position) of the wheel cover around the spindle eventhough the wheel cover is undetachably held on the housing.

In another embodiment, the outer circumference of the mounting portionof the housing and the inner circumference of the mounting part of thewheel cover may each have corrugated shapes that engage at prescribedrotational-angle positions and thereby are capable of positioning thewheel cover with respect to the housing.

In such an embodiment, it is possible to position the wheel cover at anarbitrary location (rotational position) around the spindle, and therebyto easily adjust and fix the position of the wheel cover. In addition,the mounting part on the wheel cover may be configured in acircular-ring shape with the open ends of a circular ring being coupledtogether by a fixing member. In such an embodiment, the wheel cover canbe removed from the housing by removing the fixing member and uncouplingthe open ends. Accordingly, it is possible to replace the wheel coverfor maintenance purposes at, for example, a power tool repair shop.

Furthermore, in such an embodiment, for example, a rivet as describedabove may be used as the fixing member. That is, a rivet cannot beremoved in a simple manner using a tool, and therefore the wheel covercan be undetachably held on the housing using the rivot.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view that shows the configuration of agrinder according to a first embodiment.

FIG. 2 is a cross-sectional view in which a mounting part, which mountsa wheel cover on a housing, is sectioned along (through) its slits.

FIG. 3 is a cross-sectional view that shows the state in which the wheelcover has been rotated from the position shown in FIG. 2.

FIG. 4 is an oblique view that shows the external appearance of thewheel cover attached to the grinder.

FIG. 5 is an oblique view that shows the state in which the wheel coverhas been rotated from the position shown in FIG. 4.

FIG. 6 is an oblique view that shows the configuration of the entiregrinder according to a second embodiment.

FIG. 7 is a cross-sectional view that shows the state wherein the wheelcover and the grinder are sectioned along a center axis of a spindle.

FIG. 8 is an oblique view that shows the configuration of the entiregrinder according to a third embodiment.

FIG. 9 is an oblique view that shows the configuration of a wheel cover.

FIG. 10 is a plan view that shows the state of the grinder, viewed fromthe wheel cover side, from which the wheel cover has been removed.

FIG. 11 is a cross-sectional view taken along line A-A in FIG. 10.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are explained below, with referenceto the drawings.

First Embodiment

As shown in FIG. 1, a grinder 2 of the present embodiment principallycomprises a motor housing 4, a gear housing 6, a rear cover 8, and awheel cover 10.

The motor housing 4 is substantially circular-cylindrical and houses amotor 12. A rotary shaft 14 of the motor 12 is disposed such that itprotrudes toward the gear housing 6.

The rear cover 8 is provided on one-end side of the motor housing 4 in acenter-axis direction and houses a power-supply wiring part 16. Apower-supply cord 18, which supplies electric current from an externalpower supply, and a switch 19, which switches the drive of the grinder 2ON and OFF, are provided in (as parts of) the power-supply wiring part16. The power-supply wiring part 16 is electrically connected to themotor 12.

The gear housing 6 is provided on the side of the motor housing 4opposite the rear cover 8 and houses a first bevel gear 20, a secondbevel gear 22, a spindle 24, bearings 26, 28, and the like.

The first bevel gear 20 is fixed to the rotary shaft 14 of the motor 12inside the gear housing 6. The second bevel gear 22, the spindle 24, andthe bearings 26, 28 are provided integrally with an inner housing 30,which is configured as a structure separate from the gear housing 6, andare housed inside the gear housing 6 by virtue of the inner housing 30being mated to and fixed inside the gear housing 6.

Furthermore, the inner housing 30 is fixed to the gear housing 6 bypassing headed male screws 29 (refer to FIG. 4 and FIG. 5), from theinner housing 30 side, through screw holes provided in the same axialdirection as the spindle 24 at four locations of the inner housing 30and four locations of the gear housing 6 around the spindle 24 and thenscrewing the headed male screws 29 into female threads formed in thescrew holes on the gear housing 6 side.

The spindle 24 is rotatably provided via a bearing 26 in the innerhousing 30. The inner housing 30 has a circular-cylinder shape that iscoaxial with the center axis of the spindle 24 and is fixed inside thegear housing 6 such that the spindle 24 is orthogonal to the rotaryshaft 14 of the motor 12.

The second bevel gear 22 is fixed to the spindle 24 and meshes with thefirst bevel gear 20 inside the gear housing 6, and thereby therotational output of the motor 12 is converted to a rotational forcearound the axis of the spindle 24.

One end of the spindle 24 is rotatably supported by the gear housing 6via the bearing 28, and the other end of the spindle 24 protrudesexternally from the inner housing 30 (in other words, from the gearhousing 6).

An inner flange 32 for positioning and fixing a discoidal tool accessory(not shown) is provided on the portion of the spindle 24 that protrudesfrom the gear housing 6. In addition, a threaded portion 25, onto whicha lock nut 34 is screwed, is formed on an outer-circumferential portionof the spindle 24 that is closer to the tip than the inner flange 32.The lock nut 34 is for holding the tool accessory between the lock nut34 and the inner flange 32.

In the grinder 2 configured in this manner, when the switch 19 changesto the ON state, the motor 12 rotates and the rotational output thereofis transmitted to the spindle 24 via a gear mechanism (the first bevelgear 20 and the second bevel gear 22) inside the gear housing 6.

Consequently, if the tool accessory is fixed beforehand to the spindlevia the lock nut 34, then the tool accessory rotates and thereby work,such as grinding, polishing, and cutting, can be performed. Furthermore,a grinding stone, a cutting stone, a wire brush, and the like arerepresentative, non-limiting examples of a tool accessory that may beused with the grinder 2 in this manner.

In addition, a fan 15, which draws in outside air from an inlet hole ofthe rear cover 8 and exhausts air via an exhaust hole 7 provided in thegear housing 6, is provided on the rotary shaft of the motor 12. Therotation of the fan 15 causes outside air to pass around the motor 12,thereby cooling the motor 12.

The wheel cover 10 is for protecting the user from flying debris of theworkpiece, the tool accessory, or the like generated during anoperation, such as grinding, polishing, cutting, or the like.Consequently, the wheel cover 10 is formed as substantially a semicirclesuch that the portion (more particularly, approximately half) of thetool accessory that is fixed to the spindle 24 is covered from the gearhousing 6 side.

The wheel cover 10 is fixed to the inner housing 30 at the portion wherethe spindle 24 protrudes. This fixed structure is discussed in detailbelow.

As shown in FIG. 2 and FIG. 3, on the inner housing 30, a mountingportion 40 for mounting the wheel cover 10 has a circular-cylinder shapesuch that it is coaxial with the center axis of the spindle 24 andsurrounds the spindle 24.

In addition, as shown in FIG. 1 to FIG. 5, on the wheel cover 10, asemicircular wall part 50, which makes contact with an outercircumference of the mounting portion 40 of the inner housing 30 and iscapable of pivoting around the spindle 24, extends vertically upwardfrom a center portion of a semicircular plate surface, which is disposedso as to oppose the tool accessory.

Furthermore, a circular-ring-shaped mounting part 52 is joined to thewall part 50 such that the mounting part 52 surrounds the entireouter-circumferential area of the mounting portion 40 of the innerhousing 30.

The wheel cover 10 is composed of a metal plate, the main element ofwhich is iron, and the wall part 50 is formed integrally with the wheelcover 10 by press molding or the like. In addition, the mounting part 52is composed of an elongated metal plate, the main element of which isiron, and is formed into a circular-ring shape by press molding or thelike. Furthermore, open ends of the circular ring of the mounting part52 are bent toward the outer side of the circular ring such that themounting part 52 can be tightened in a radial direction by a tighteningmember 58 (refer to FIG. 2, FIG. 3, and the FIG. 5). Furthermore, in thepresent embodiment, the tightening member 58 comprises a headed malescrew 58A and a nut 58B.

The mounting part 52 is joined to the wheel cover 10 by welding or thelike such that the mounting part 52 surrounds the wall part 50 of thewheel cover 10. Furthermore, elongated slits 54A, 54B (identified asmerely 54 in FIG. 1) are formed in the mounting part 52 and in the wallpart 50 of the wheel cover 10, to which the mounting part 52 is joined,along a circumferential direction of the circular ring of the mountingpart 52 such that the slits 54A, 54B pass through from the outer side tothe inner side of the circular ring.

The slits 54A, 54B are formed in two areas that extend from the open-endsides of the circular ring of the mounting part 52 to the side oppositethe open ends such that the center axis of the circular ring isinterposed therebetween, as shown by arrows in FIG. 2 and FIG. 3.

Headed male screws 56A, 56B, the heads of which are larger than thewidths of the slits 54A, 54B, are inserted through the two slits 54A,54B, respectively, from the outer side of the mounting part 52.Furthermore, the male screws 56A, 56B are fixed in female threads 57A,57B, respectively, provided in the mounting portion 40 of the innerhousing 30. The headed male screws 56A, 56B may alternatively be formedas bolts with heads wider than the narrow width of the slits or as rodswith heads wider than the narrow width of the slits.

Furthermore, in the mounting portion 40 of the inner housing 30, thefemale threads 57A, 57B, in which the male screws 56A, 56B are fixed,are formed at locations substantially opposing one another andsandwiching the center axis of the mounting portion 40.

As a result, as can be understood from FIG. 2 and FIG. 3 or from FIG. 4and FIG. 5, the wheel cover 10 is capable of pivoting around the spindle24 by the rotational-angle range (about 180°) in which the slits 54A,54B are formed.

Thus, in the grinder 2 of the present embodiment, the circular-ringshaped mounting part 52, which is integrally assembled with the wheelcover 10, is mated to the mounting portion 40 of the inner housing 30,from which the spindle 24 protrudes.

Furthermore, the male screws 56A, 56B pass through the slits 54A, 54Bformed in the mounting part 52 and are fixed in the female threads 57A,57B of the mounting portion 40; thereby, the wheel cover 10 is held onthe inner housing 30.

According to the grinder 2 of the present embodiment, to remove thewheel cover 10 from the grinder 2, it is necessary to remove the malescrews 56A, 56B, which are holding members, from the mounting portion 40of the inner housing 30, and that removal work is labor-intensive.Consequently, it is possible to prevent the user from removing the wheelover 10 and then using the grinder 2 with the wheel cover 10 removed.

In addition, the mounting portion 40 of the inner housing 30 is acircular cylinder that is coaxial with the center axis of the spindle24, and consequently the wheel cover 10 can pivot around the spindle 24although the pivotable range is limited by the length of the slits 54A,54B in the circumferential direction.

Consequently, the user can arbitrarily set the arrangement and positionof the wheel cover 10 around the spindle 24—in other words, thearrangement and position of the area covered by the tool accessory fixedto the spindle 24—and therefore the ergonomics or usability of thegrinder 2 is (are) not diminished.

Furthermore, in the wheel cover 10, the open ends of the circular ringof the mounting part 52 are bent toward the outer side of the circularring, the male screw 58A, which (together with the nut 58B) constitutesthe tightening member 58, passes through those bent portions. Byscrewing it into the nut 58B, the male screw 58A can tighten the wheelcover 10 in the radial direction.

Consequently, after the user sets the arrangement and (rotational)position of the wheel cover 10 around the spindle 24, the user canposition and fix the wheel cover 10 around the spindle 24 by tighteningthe mounting part 52 of the wheel cover 10 in the radial direction viathe tightening member 58.

Thereby, it is possible to prevent the position of the wheel cover 10from shifting with respect to the tool accessory when the grinder 2 isbeing used, which would be disadvantageous.

In addition, the male screws 56A, 56B, which serve as the holdingmembers, are fixed (screw-fastened) at two locations that substantiallydivide the outer circumference of the mounting portion 40 of the innerhousing 30 into two, and the two slits 54A, 54B, which are for the malescrews 56A, 56B to be inserted into, are formed in the mounting part 52of the wheel cover 10.

Consequently, according to the grinder 2 of the present embodiment, thewheel cover 10 can be held on the inner housing 30 by the male screws56A, 56B such that the center axis of the inner housing 30 (and in turn,the spindle 24) and the center axis of the wheel cover 10 substantiallycoincide.

Accordingly, when the rotational position of the wheel cover 10 is beingadjusted by pivoting it around the spindle 24, it is possible to preventthe center axis of the wheel cover 10 from tilting with respect to thecenter axis of the mounting portion 40 of the inner housing 30 andthereby making the positional adjustment easy to perform withoutdisadvantageous results.

Furthermore, in the present embodiment, because the headed male screws56A, 56B, which serve as the holding members, are used, the wheel cover10 would be easy to remove from the grinder if the heads of the malescrews 56A, 56B were to have a shape that corresponds to a common tool(e.g., a flat screwdriver or a Phillips-head screwdriver).

Consequently, the heads of the male screws 56A, 56B are insteadpreferably shaped such that the male screws 56A, 56B can mate only witha special tool that is not commercially available and should be madesuch that the male screws 56A, 56B cannot be unscrewed from the innerhousing 30 in a simple manner.

In addition, to that end, the male screws 56A, 56B may be bonded to theinner housing 30 by using, for example, a screw-fixing adhesive. Inaddition, the heads of the male screws 56A, 56B may be crushed orotherwise deformed so that the male screws 56A, 56B cannot be unscrewedfrom the inner housing 30 using a tool.

Second Embodiment

As shown in FIG. 6 and FIG. 7, the grinder 2 of the present embodimenthas the same basic configuration as the first embodiment but differsfrom the first embodiment in that rivets 60A, 60B (in the drawings, onlythe rivet 60A is shown), which serve as fixing members, are substitutedfor the male screws 56A, 56B.

Furthermore, in FIGS. 6, 7, the structural elements, other than therivets 60A, 60B, are the same as those in the first embodiment;structural elements the same as those in the first embodiment areassigned the same reference numerals, and explanations thereof areomitted.

As shown in FIG. 6 and FIG. 7, in the grinder 2 of the presentembodiment, the rivets 60A, 60B, instead of the male screws 56A, 56B,are inserted through the slits 54A, 54B formed in the wall part 50 ofthe wheel cover 10 and in the mounting part 52.

Furthermore, as shown in FIG. 7, instead of the female threads 57A, 57B,the rivets 60A, 60B are driven into and mated in holes 61A, 61B (in thedrawings, only the hole 61A is shown) formed in the mounting portion 40of the inner housing 30. As a result, the wheel cover 10 is held on theinner housing 30 so as to be pivotable via the rivets 60A, 60B.

Thereby, the grinder 2 of the present embodiment can likewise achievethe same effects as those of the first embodiment. In addition, byvirtue of being driven into the holes 61A, 61B, the rivets 60A, 60B aremore difficult to remove as compared with the male screws 56A, 56B, andtherefore it is possible to more satisfactorily prevent the wheel cover10 from being removed from the grinder 2.

Third Embodiment

As shown in FIG. 8 to FIG. 11, the grinder 2 of the present embodimenthas the same basic configuration as the first and second embodiments,but differs from the above-mentioned embodiments in the wall part 50 ofthe wheel cover 10, the mounting portion 40 of the inner housing 30, anda tightening member 62.

Accordingly, in the present embodiment, in FIG. 8 to FIG. 11, structuralelements the same as those of the above-mentioned embodiments areassigned the same reference numerals, and explanations thereof areomitted while points of difference are explained.

As shown in FIG. 8 and FIG. 10, the outer-circumferential surface of themounting portion 40, on which the wheel cover 10 in the inner housing 30is attached, is a corrugated shape having convex and concave shapesformed at prescribed rotational angles around the center axis of theinner housing 30 (in other words, the spindle 24).

In addition, as shown in FIG. 9, the wheel cover 10 includes the wallpart 50, which makes contact with the mounting portion 40 of the innerhousing 30, that likewise has a corrugated shape that corresponds to theouter-circumferential surface of the mounting portion 40.

Furthermore, as in the above-mentioned embodiments, the ring-shapedmounting part 52 is joined, from the outer side, to the wall part 50 ofthe wheel cover 10 by welding or the like. Consequently, substantiallyhalf of an inner-circumferential surface of the mounting part 52 assumesa corrugated shape that corresponds to the outer-circumferential surfaceof the mounting portion 40 of the inner housing 30.

Accordingly, if the wheel cover 10 is pivoted around the spindle 24 inthe state in which the wheel cover 10 is attached to the inner housing30, then the wheel cover 10 becomes positioned at an arbitraryrotational-angle position at which the corrugations formed on theouter-circumferential surface of the mounting portion 40 and on theinner-circumferential surface of the mounting part 52 overlap (engage)one another.

In addition, as shown in FIG. 9, projections 51 extend vertically upwardon the wall part 50 of the wheel cover 10 on both end sides in thecircumferential direction of the semicircular shape. Furthermore, FIG. 9shows the state of the wheel cover 10 before the mounting part 52 isjoined to the wall part 50 by welding or the like.

On the other hand, as shown in FIG. 11, a groove 42 is formedsubstantially around the entire outer-circumferential surface of themounting portion 40 of the inner housing 30. The inner-circumferentialsurface of the wall part 50 of the wheel cover 10 makes contact with theouter-circumferential surface of the mounting portion 40.

When the wheel cover 10 is to be mounted to the mounting portion 40 ofthe inner housing 30 by using the mounting part 52, the projections 51are inserted into the groove 42 and can be slid along the groove 42 whenthe wheel cover 10 is pivoted around the spindle 24.

Consequently, once the wheel cover 10 is attached to the inner housing30, the diameter of the mounting part 52 widens and thereby the wheelcover 10 cannot be moved in the center-axis direction of the spindle 24and can not be removed from the inner housing 30 unless the projections51 are taken out of the groove 42.

Furthermore, in the present embodiment, a rivet is used as thetightening member 62 that couples the open ends of the mounting part 52such that the wheel cover 10 cannot be removed from the inner housing 30(in other words, so that the wheel cover 10 is undetachable). This rivetis a type wherein the rivet is passed through the holes in the openends, the rivet is upset on both sides using a tool, and thereby lockingheads are formed on both sides of the holes.

Consequently, after the mounting part 52 is fixed by tightening themounting part 52 around the mounting portion 40 of the inner housing 30by using the tightening member 62, which is a rivet, the wheel cover 10can no longer be removed from the grinder 2.

In addition, the wheel cover 10 is capable of pivoting around thespindle 24 by sliding the projections 51, which extend upward on thewall part 50 that constitutes part of the inner-wall surface of themounting part 52, along the groove 42 formed on theouter-circumferential surface of the mounting portion 40 of the innerhousing 30.

Furthermore, that pivot position is located at any arbitraryrotational-angle position at which the corrugation formed on theouter-circumferential surface of the mounting portion 40 of the innerhousing 30 and the corrugation formed on the wall part 50, which is theinner-circumferential surface of the mounting part 52, overlap (engage)one another. Accordingly, in the present embodiment, the wheel cover 10can be easily positioned around the spindle 24.

Representative, non-limiting embodiments of the present teachings areexplained above, but the present invention is not limited to theabove-mentioned embodiments and it is understood that variations andmodifications may be effected without departing from the spirit andscope of the invention.

For example, the above-mentioned embodiments explain that the wheelcover 10 is held on the inner housing 30, in which the spindle 24 isprovided, but the wheel cover 10 may be held on the gear housing 6, inwhich the inner housing 30 is housed.

In addition, grinders according to the present teachings may beconfigured such that the gear housing 6 is integrated with the innerhousing 30. In such an embodiment, the spindle 24, the first bevel gear20, the second bevel gear 22, the bearings 26, 28, and the like are allprovided directly in the gear housing 6.

Moreover, in the first and second embodiments, the wheel cover 10 isprevented from being removed from the grinder 2 while permitting thepivoting of the wheel cover 10 around the spindle 24 by providing theslits 54A, 54B and by the male screws 56A, 56B or by providing therivets 60A, 60B inserted into the slits 54A, 54B. In addition, the thirdembodiment achieves the same effects by using the groove 42 and theprojections 51.

On the other hand, the same effects can be achieved even if, forexample, the ring-shaped mounting part 52 of the wheel cover 10 isexternally fitted on the mounting portion of the housing of the grinder2 and then the diameter of the open ends of the ring shape of themounting portion are widened.

In addition, the first and second embodiments explained that the numberof the male screws 56A, 56B or the rivets 60A, 60B, which serve as theholding members, is two, but the number may be one or may be three ormore. In addition, in the third embodiment, the number of theprojections 51 inserted into the groove 42 may be three or more, and maybe ridges instead of projections.

In addition, each of the above-mentioned embodiments explain that themounting part 52 of the wheel cover 10 is integrally joined to the wallpart 50 of the wheel cover 10, but the mounting part 52 may beintegrally formed together with the wheel cover 10.

Representative, non-limiting examples of the present invention weredescribed above in detail with reference to the attached drawings. Thisdetailed description is merely intended to teach a person of skill inthe art further details for practicing preferred aspects of the presentteachings and is not intended to limit the scope of the invention.Furthermore, each of the additional features and teachings disclosedabove and below may be utilized separately or in conjunction with otherfeatures and teachings to provide improved power tools, such asgrinders.

Moreover, combinations of features and steps disclosed in the abovedetailed description, as well as in the below additional examples, maynot be necessary to practice the invention in the broadest sense, andare instead taught merely to particularly describe representativeexamples of the invention. Furthermore, various features of theabove-described representative examples, as well as the variousindependent and dependent claims below, may be combined in ways that arenot specifically and explicitly enumerated in order to provideadditional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intendedto be disclosed separately and independently from each other for thepurpose of original written disclosure, as well as for the purpose ofrestricting the claimed subject matter, independent of the compositionsof the features in the embodiments and/or the claims. In addition, allvalue ranges or indications of groups of entities are intended todisclose every possible intermediate value or intermediate entity forthe purpose of original written disclosure, as well as for the purposeof restricting the claimed subject matter.

EXPLANATION OF THE REFERENCE NUMBERS

-   2 Grinder-   4 Motor housing-   6 Gear housing-   7 Exhaust hole-   8 Rear cover-   10 Wheel cover-   12 Motor-   14 Rotary shaft-   15 Fan-   16 Power-supply wiring part-   18 Power-supply cord-   19 Switch-   20 First bevel gear-   22 Second bevel gear-   24 Spindle-   25 Threaded portion-   26, 28 Bearings-   30 Inner housing-   32 Inner flange-   34 Lock nut-   40 Mounting portion-   42 Groove-   50 Wall part-   51 Projection-   52 Mounting part-   54A, 54B Slits-   56A, 56B Male screws-   57A, 57B Female threads-   58, 62 Tightening members-   60A Rivet

1. A grinder, comprising: a motor; a housing that houses the motor; aspindle that projects from the housing and is driven by the motor, andthereby rotates relative to the housing; a wheel cover that is disposedon an outer-circumference side of the spindle projecting from thehousing and that is configured to cover a portion of a tool accessoryattached to the spindle; and means for holding the wheel cover on thehousing; wherein the wheel cover and the holding means are configuredsuch that, in the state wherein the wheel cover is held on the housingby the holding means, the arrangement and position of the wheel coveraround the spindle can be changed.
 2. The grinder according to claim 1,wherein the holding means comprises at least one holding memberconfigured as a separate structure from the wheel cover, the at leastone holding member being configured to hold the wheel cover on thehousing.
 3. The grinder according to claim 2, wherein: the housingincludes a mounting portion, to which the wheel cover is attached, thathas a circular-cylinder shape and that surrounds the spindle; the wheelcover is configured to be externally fitted onto the mounting portion ofthe housing and comprises a circular-ring-shaped mounting part, themounting part including an outwardly facing circumferential slit; andthe at least one the holding member comprises a rivet or a screwextending into the slit of the mounting part of the wheel cover, one endof the rivet or screw being fixed to the mounting portion of the housingand the other end of the rivet or screw having a head larger than awidth of the slit.
 4. The grinder according to claim 3, wherein: the atleast one holding member comprises a plurality of holding members thatare distributed over, and fixed at, a plurality of locations of theouter circumference of the mounting portion of the housing.
 5. Thegrinder according to claim 3, wherein: the wheel cover includes atightening member on the mounting part configured to tighten and therebyfix the mounting part on the outer circumference of the mounting portionof the housing.
 6. The grinder according to claim 1, wherein: thehousing includes a mounting portion, to which the wheel cover isattached, that has a circular-cylinder shape that surrounds the spindle;the wheel cover comprises a circular-ring-shaped mounting partconfigured to be externally fitted onto the mounting portion of thehousing; and the holding means comprise a circumferential groove formedon one of an outer circumference of the mounting portion of the housingand an inner circumference of the mounting part of the wheel cover and aprojection or ridge on the other one of the mounting portion and themounting part, the projection or ridge extending into the groove andbeing configured to slide within the groove.
 7. The grinder according toclaim 1, wherein: an outer circumference of a mounting portion of thehousing and an inner circumference of a mounting part of the wheel covereach have corrugated shapes that engage at prescribed rotational-anglepositions and thereby are capable of positioning the wheel cover withrespect to the housing.
 8. The grinder according to claim 2, wherein theholding means undetachably holds the wheel cover on the housing.
 9. Thegrinder according to claim 5, wherein the holding means undetachablyholds the wheel cover on the housing.
 10. A grinder, comprising: amotor; a housing that houses the motor; a spindle that projects from thehousing and is driven by the motor and thereby rotates relative to thehousing; and a wheel cover disposed on an outer-circumference side ofthe spindle projecting from the housing and being configured to cover aportion of a tool accessory attached to the spindle and to pivotrelative to the spindle; wherein the wheel cover is configured such thatit is undetachably held on the housing.
 11. The grinder according toclaim 10, wherein: the housing includes a mounting portion, to which thewheel cover is attached, that has a circular-cylinder shape andsurrounds the spindle; the wheel cover comprises a circular-ring-shapedmounting part configured to be externally fitted onto the mountingportion of the housing; and one of an outer circumference of themounting portion of the housing and an inner circumference of themounting part of the wheel cover has a groove that is formed along acircumferential direction, and the other one has a projection or aridge, which is inserted into the groove and is capable of slidingwithin the groove.
 12. The grinder according to claim 11, wherein: theouter circumference of the mounting portion of the housing and the innercircumference of the mounting part of the wheel cover each havecorrugated shapes that engage at prescribed rotational-angle positionsand thereby are capable of positioning the wheel cover with respect tothe housing.
 13. The grinder according to claim 11, wherein: themounting part on the wheel cover is configured in a circular-ring shapesuch that open ends of a circular ring are coupled together by a fixingmember.
 14. The grinder according to claim 10, wherein: the housingincludes a mounting portion, to which the wheel cover is attached, thathas a circular-cylinder shape and that surrounds the spindle; the wheelcover is configured to be externally fitted onto the mounting portion ofthe housing and comprises a circular-ring-shaped mounting part having anoutwardly facing circumferential slit; and a rivet or a screw extendsfrom the mounting portion into the slit of the mounting part of thewheel cover, one end of the rivet or screw being fixed to the mountingportion of the housing and the other end of the rivet or screw having ahead larger than a width of the slit.
 15. The grinder according to claim10, further comprising at least one rod projecting from the housing andextending through at least one circumferential slit in the wheel cover.16. A grinder, comprising: a housing including a cylindrical mountingportion; a motor in the housing; a spindle operatively connected to themotor, the spindle projecting from the cylindrical mounting portion andbeing configured to be driven by the motor and to rotate relative to thehousing; a wheel cover including a ring-shaped mounting part mounted onthe cylindrical mounting portion and a covering part radially spacedfrom and extending partially around the spindle, the covering part beingconfigured to cover a portion of a tool accessory attached to thespindle, the mounting portion including a first circumferential slithaving first and second ends; and a first rod projecting from themounting portion and extending through the first circumferential slit,the first rod having a head larger than an axial width of the firstcircumferential slit, the wheel cover being shiftable between a firstportion in which the first rod contacts the first end of the firstcircumferential slit and a second position in which the first rodcontacts a second end of the first circumferential slit.
 17. The grinderaccording to claim 16, wherein: the mounting portion includes a secondcircumferential slit and the grinder includes a second rod projectingfrom the mounting portion through the second circumferential slit, thesecond rod having a head larger than a width of the secondcircumferential slit.
 18. The grinder according to claim 17, wherein thewheel cover is undetachably held on the housing.
 19. The grinderaccording to claim 16, wherein the wheel cover is captively held on thehousing.